sysdeps/ieee754/ldbl-128/s_llroundl.c

   1 /* Round long double value to long long int.
   2    Copyright (C) 1997, 1999, 2004 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and
   5                   Jakub Jelinek <jj@ultra.linux.cz>, 1999.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Lesser General Public
   9    License as published by the Free Software Foundation; either
  10    version 2.1 of the License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Lesser General Public License for more details.
  16
  17    You should have received a copy of the GNU Lesser General Public
  18    License along with the GNU C Library; if not, write to the Free
  19    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20    02111-1307 USA.  */
  21
  22 #include <math.h>
  23
  24 #include "math_private.h"
  25
  26
  27 long long int
  28 __llroundl (long double x)
  29 {
  30   int64_t j0;
  31   u_int64_t i1, i0;
  32   long long int result;
  33   int sign;
  34
  35   GET_LDOUBLE_WORDS64 (i0, i1, x);
  36   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  37   sign = (i0 & 0x8000000000000000ULL) != 0 ? -1 : 1;
  38   i0 &= 0x0000ffffffffffffLL;
  39   i0 |= 0x0001000000000000LL;
  40
  41   if (j0 < 48)
  42     {
  43       if (j0 < 0)
  44         return j0 < -1 ? 0 : sign;
  45       else
  46         {
  47           i0 += 0x0000800000000000LL >> j0;
  48           result = i0 >> (48 - j0);
  49         }
  50     }
  51   else if (j0 < (int32_t) (8 * sizeof (long long int)) - 1)
  52     {
  53       if (j0 >= 112)
  54         result = ((long long int) i0 << (j0 - 48)) | (i1 << (j0 - 112));
  55       else
  56         {
  57           u_int64_t j = i1 + (0x8000000000000000ULL >> (j0 - 48));
  58           if (j < i1)
  59             ++i0;
  60
  61           if (j0 == 48)
  62             result = (long long int) i0;
  63           else
  64             result = ((long long int) i0 << (j0 - 48)) | (j >> (112 - j0));
  65         }
  66     }
  67   else
  68     {
  69       /* The number is too large.  It is left implementation defined
  70          what happens.  */
  71       return (long long int) x;
  72     }
  73
  74   return sign * result;
  75 }
  76
  77 weak_alias (__llroundl, llroundl)